(a) Field of the Invention
The invention relates to a lens-testing apparatus and a lens-testing method for testing a lens device, and more particularly, to a lens-testing apparatus and a lens-testing method for generating a plurality of combinations of object distances to test a lens device.
(b) Description of the Related Art
A lens device is wildly applied in optical devices, such as digital camera. During the manufacturing process, the quality of the lens device varies with the manufacturing difference. As a result, before delivered out of the factory, the lens device should be tested to confirm that the lens device can conform to the specification of original design.
FIG. 1 shows a schematic diagram illustrating a conventional light box for testing a lens device. Referring to FIG. 1, the light box 10 comprises a housing 11 and a loading platform 12, a light source 13, at least one image sensor 14, a host computer 15, a test chart 16 and a lens device 17 which are disposed in the housing 11. For testing different properties of the lens device 17, different test charts 16 may be used. For example, during the test, light from the light source 13 shed on the test chart 16 passes through the lens device 17 and then is shed on the image sensor 14. The image sensor 14 captures an image and transmits it to the host computer 15. The host computer 15 is used to analyze the image captured and then the property of an image sensor 14 such as resolution, opto-electronic conversion function (OECF), gray value, modulation transfer function (MTF), spatial frequency response, etc. may be obtained.
However, the conventional light box 10 only can examine the lens device 17 at an object distance at a time. If the lens device 17 is requested to be examined at different object distances, a transmission device 18 should be provided in the conventional light box 10 to change the distance between the image sensor 14 and the lens device 17. In addition, when the conventional light box 10 is used to examine a lens device at a large viewing angle or at a long object distance, it has to have a huge volume. Furthermore, the place for containing it has also to be a big space, so that the place is limited and the space thereof is wasted.